The majority of cosmetic or dermopharmaceutical compositions consist of a fatty phase, the oily products of which have a certain tendency to oxidize, even at room temperature. The consequence of this oxidation is to profoundly modify the properties, especially olfactory, thereof, which makes them unusable after a variable time period.
In order to protect the compositions with respect to these oxidation phenomena, it is common practice to incorporate protective agents which act as antioxidizing agents.
Among the most commonly used antioxidizing products, there may be mentioned ascorbic acid, which acts in particular by direct absorption of oxygen, but it has, however, the disadvantage of being very sparingly soluble in fats, which consequently does not enable them to be well protected.
With a view to overcoming the disadvantages of ascorbic acid, various antioxidizing systems have been recently proposed, in particular in French Patent No. 90 11384 (2,666,809), the latter consisting of at least one tocopherol or tocopherol derivative and at least one non-thiolated polypeptide.
Likewise, in French Patent No. 88 10295 (2,634,779), it has been suggested to use an antioxidizing system consisting of a tocopherol or a mixture of tocopherols, or of caffeic acid or one of its derivatives, of at least one complexing agent and of at least one non-thiolated polypeptide.
These antioxidizing systems have a particularly pronounced synergic effect, but they are nevertheless prone to pose problems of preservation during lengthy storage periods.
If the antioxidizing agents are particularly useful for the correct preservation of the fats in cosmetic or dermopharmaceutical compositions, it is also acknowledged that the latter, in certain applications, can also make it possible to efficiently combat the harmful effects of peroxides, especially organic peroxides formed by the action of atmospheric pollutants and of ultraviolet radiation.
Living cells have in fact various natural means of defence against lipid peroxides, in particular epidermal glutathione peroxidase, but its detoxifying efficiency is greatly reduced under the influence of exposure to ultraviolet radiation.
It is therefore important to be able to have available antioxidizing agents capable of inhibiting the formation of free radicals which are a source of oxidation phenomena which can cause irreversible cell damage.